A unit pixel included in a pixel array of a CMOS image sensor, which is a typical example of a solid-state imaging device, includes a photodiode that performs photoelectric conversion, a read transistor that reads a signal charge converted and accumulated in the photodiode to a floating diffusion (floating diffusion layer, hereinafter referred to as “FD”) which functions as a capacity element, a reset transistor that sets a voltage of the FD to a power source voltage, and an amplifying transistor that converts the voltage of the FD into a pixel signal when forming a source follower circuit by using a current source connected to a vertical signal line and outputs the pixel signal to the vertical signal line.
By the way, in recent years, miniaturization of the unit pixel has advanced due to a request to increase the number of pixels or reduce the size of optical system. As the pixel size reduces, a case occurs in which the charge accumulation capacity (dynamic range) of the FD is not sufficient with respect to the converted signal charge amount of the photodiode depending on the brightness (illumination intensity) of the subject, and there is a problem that all the signal charge converted and accumulated in the photodiode may not be read to the FD.